Poly(silethynylenedisiloxane) and method for the manufacture thereof

ABSTRACT

Silethynylenedisiloxane polymers are described with repeating units represented by --R 1  R 2  SiC.tbd.CSiR 3  R 4  OSiR 5  R 6  O-- where R 1  -R 6  independently represent hydrogen atoms, alkyl groups, aryl groups, or alkenyl groups. The polymers are prepared by reacting a disilylacetylene compound represented by the formula X 1  R 1  R 2  SiC.tbd.CSiR 3  R 4  X 1  and a silane compound represented by the formula X 2   2  SiR 5  R 6  where X 1  and X 2  represent H, OH, OM, or a hydrolyzable group. X 1  and X 2  are not identical and are selected so that they undergo a condensation reaction to form a siloxane bond.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention concerns novel organosilicon polymers and a methodfor their manufacture, more specifically poly(silethynylenedisiloxane)having alternating silethynylene units and siloxane units, such that themain skeleton of the polymer has repeating units of the formula--SiC.tbd.CSiOSiO--.

There have been numerous reports of polymers with mainchain repeatingunits containing an ethynylene group (--C.tbd.C--) bonded to a siliconatom. Also, there have been many reports of polymers having both asilicon-bonded ethynylene group and a siloxane group in the main-chainrepeating units. For example, British Patent No. 2234517 disclosed amethod for the manufacture of random copolymers of the --SiC.tbd.C--unit and --SiO-- unit using a lithium catalyst.

However, such conventional polymers lack regularity in structure. Inparticular, there have not been any reports on polymers consisting ofcompletely alternating silethynylene unit and siloxane unit, such as--SiC.tbd.CSiOSiO--, as the main skeleton. Here, it is an objective ofthe present invention to provide polymers with completely alternatingsilethynylene units and siloxane units, such as --SiC.tbd.CSiOSiO--, asthe main skeleton.

As a result of an intense investigation of ways to achieve suchobjectives, we have succeeded in synthesizingpoly(silethynylenedisiloxane) with repeating units represented by theformula:

    --R.sup.1 R.sup.2 SiC.tbd.CSiR.sup.3 R.sup.4 OSiR.sup.5 R.sup.6 O--(I)

In the formula, R¹ -R⁶ independently represent hydrogen atoms, alkylgroups, aryl groups, or alkenyl groups.

SUMMARY OF THE INVENTION

The present invention comprises silethynylenedisiloxane polymers withrepeating units represented by the formula --R¹ R² SiC.tbd.CSiR³ R⁴OSiR⁵ R⁶ O-- where, R¹ -R⁶ independently represent hydrogen atoms, alkylgroups, aryl groups, or alkenyl groups. The polymer are prepared byreacting a disilylacetylene compound represented by the formula X¹ R¹ R²SiC.tbd.CSiR³ R⁴ X¹ and a silane compound represented by the formula X²₂ SiR⁵ R⁶ where X¹ and X² represent H, OH, OM, or a hydrolyzable groupand X¹ and X² may undergo a condensation reaction to form a siloxanebond.

DESCRIPTION OF THE INVENTION

The poly(silethynylenedisiloxanes) of the present invention are linearpolymers having the unit represented by formula (I). As described above,the polymers of completely alternating silethynylene units--SiC.tbd.CSi-- and siloxane units, --OSiO-- such as --those with--SiC.tbd.CSiOSiO-- as the main skeleton, are novel. Polymers of suchstructures have a high heat resistance and oxidation resistance, goodelectrical properties (insulation), processability, and strength, thusthey are useful for coatings, films, and other applications.

For the poly(silethynylenedisiloxanes) of the present invention, thereare no particular restrictions on the degree of polymerization (numberof repeating units), while a degree of polymerization above 3 ispreferred to display the needed properties of the polymers. Also, adegree of polymerization below 10,000 is preferred in terms of theprocessability and solubility in solvents.

The R¹ -R⁶ substituents bonded to the silicon atom can be chosen from ahydrogen atom; alkyl groups such as a methyl, ethyl, propyl, butyl,pentyl, hexyl, etc.; aryl groups such as a phenyl, tolyl, xylyl,mesityl, etc.; alkenyl groups such as a vinyl, allyl, propenyl, butenyl,etc., while a methyl group or phenyl group is preferred in economicterms. In particular, the silethynylene-siloxane copolymer containing aphenyl group as the substituent bonded to a silicon atom has excellentheat resistance, but there have not been any reports on randomcopolymers. R¹ -R⁶ usually have less than 20 carbon atoms.

The present invention provides a method for the manufacture ofpoly(silethynylenedisiloxane), with repeating units represented byformula (I), by reacting a disilylacetylene compound represented by theformula,

    X.sup.1 R.sup.1 R.sup.2 SiC.tbd.CSiR.sup.3 R.sup.4 X.sup.1 (II)

with a silane compound represented by the formula,

    X.sup.2.sub.2 SiR.sup.5 R.sup.6                            (III)

In formulas (II) and (III), X¹ and X² represent hydrogen atoms, hydroxygroups, alkali-metal oxide groups of the formula --OM (where M is analkali-metal atom) and hydrolyzable groups. The X¹ bonded to the siliconatom of compound (II) and the X² bonded to the silicon atom of formula(III) are selected from the above groups so that X¹ and X² may undergo acondensation reaction to form a siloxane bond. Here, to obtainalternating copolymers, it is necessary that X¹ and X² are notidentical. For example, when X¹ is a hydroxy group, X² may be a hydrogenatom or a hydrolyzable group. When X¹ is a hydrogen atom or hydrolyzablegroup, X² is a hydroxy group. Similarly, combinations of the --OM group(M is an alkali metal such as lithium, potassium, sodium, etc.) andhalogen atoms can be used.

Any conventionally known hydrolyzable groups may be used, e.g., ahalogen atom; amino groups such as a dimethylamino group, diethylaminogroup, etc.; amide groups such as an N-methylacetamide group, benzamidegroup, etc.; aminoxy groups such as a dimethylaminoxy group,diethylaminoxy group, etc.; alkoxy groups such as a methoxy group,ethoxy group, propoxy group, butoxy group, etc.; acyloxy groups such asan acetoxy group, acryloxy group, etc.; alkenyloxy groups such as anisopropenyloxy group, etc.

The siloxane-formation reaction may be carried out in a solvent orwithout a solvent. To obtain polymers with high molecular weights, usinga small amount of solvent is preferred. Any solvent that dissolves thecompounds of formulas (II) and (II) and the polymer formed, and shows noadverse effects on the reaction, can be used. The solvents are aliphatichydrocarbons such as pentane, hexane, heptane, octane, etc.; aromatichydrocarbons such as benzene, toluene, xylene, etc.; ethers such asdiethyl ether, dibutyl ether, diphenyl ether, dioxane, tetrahydrofuran,etc.; esters such as ethyl acetate, butyl acetate, etc.; ketones such asacetone, methyl ethyl ketone, methyl butyl ketone, etc.; halogenatedsolvents such as carbon tetrachloride, chloroform, trichloroethane,trichloroethylene, tetrachloroethylene, etc.; dimethylformamide;dimethyl sulfoxide; and hexamethylphosphoric triamide.

While not restricted in any particular way, the siloxane-formationreaction between compounds (II) and compound (III) may be carried outfrom a low temperature of -80° C. to a high temperature of 200° C., butan excessively high temperature may cause thermal polymerization of theethynylene group, thus it is not favored. Any pressure ranging fromvacuum pressure to a high pressure may be used.

Good results are obtained from reactions carried out in the presence ofa catalyst and an acid or base scavenger. For example, when X¹ is ahydrogen atom and X² is a hydroxy group (or vice versa), catalystseffective for dehydrogenation, such as compounds containing metal atomslike tin, titanium, palladium, etc., alkali catalysts, and amines arepreferred. When X¹ is a hydrolyzable group, especially a halogen atom,and X² is a hydroxy group (or vice versa), the addition of the compoundsscavenging the hydrogen halide formed, such as amines, e.g.,triethylamine, pyridine, etc., alkaline compounds, e.g., sodiumhydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide,etc., is preferred.

The polymers obtained with the unreacted X¹ and X² terminals may be usedwithout further modification or may be treated with alcohols, etc., forreduced reactivity. As explained above, thepoly(silethynylenedisiloxane) compounds represented by formula (I) ofthe present invention are novel polymers, which are heat-resistant anduseful in coatings, adhesives, films, structural materials, etc.

Next, the present invention is explained and demonstrated with examples.In the examples, the weight-average molecular weight was determined bygel permeation chromatography (GPC) with poly(dimethylsiloxane) asstandard. ²⁹ Si-NMR means silicon 29 nuclear magnetic resonance, withtetramethylsilane used as the external standard, at 0 ppm.

EXAMPLE 1

In a flask, 40 mL of tetrahydrofuran and 4.22 g (0.01 mol) ofbis(hydroxydiphenylsilyl)acetylene were added, then the resultingmixture was stirred in an argon atmosphere with the flask cooled to 0°C., while a solution of 3.26 g (0.01 mol) ofbis(N-methylacetomido)diphenylsilane in tetrahydrofuran (20 mL) wasslowly added dropwise. After the reaction, the mixture was poured into 1L of methanol to obtain a white polymer precipitate.

Yield 93%. Weight-average molecular weight 6300. ²⁹ Si-NMR, -38.1 ppm,-43.6 ppm, repeating unit: --Ph₂ SiC.tbd.CSiPh₂ OSiPh₂ O-- (Ph=phenylgroup)

EXAMPLE 2

In a flask, 60 mL of tetrahydrofuran and 9.78 g (0.03 mol) ofbis(N-methylacetamido)diphenylsilane were added, then the resultingmixture was stirred in an argon atmosphere with the flask cooled to 0°C., while a solution of 12.66 g (0.03 mol) ofbis(hydroxydiphenylsilyl)acetylene in tetrahydrofuran (120 mL) wasslowly added dropwise. After the reaction, the mixture was poured into1000 mL of methanol to obtain a white polymer precipitate.

Yield 95%. Weight-average molecular weight 20,000. ²⁹ Si-NMR, -38.1 ppm,-43.6 ppm, repeating unit: --Ph₂ SiC.tbd.CSiPh₂ OSiPh₂ O-- (Ph=phenylgroup)

EXAMPLE 3

In a flask, 30 mL of tetrahydrofuran, 4.6 g (0.01 mol) ofbis(chlorodiphenylsilyl)acetylene, and 3.0 g (0.03 mol) of triethylaminewere added, then and the resulting mixture was stirred in an argonatmosphere with the flask cooled to 0° C., while a solution of 2.16 g(0.01 mol) of diphenylsilanediol in tetrahydrofuran (20 mL) was slowlyadded dropwise. After the reaction, the mixture was poured into 400 mLof methanol to obtain a light reddish white polymer precipitate.

Yield 48%. Weight-average molecular weight 2200. ²⁹ Si-NMR showed askeletal structure similar to that of the polymer obtained in Example 1.

EXAMPLE 4

In a flask, 50 mL of tetrahydrofuran and 2.3 g (0.01 mol) ofdiphenylsilanediol lithium salt were added, then the resulting mixturewas stirred in an argon atmosphere with the flask cooled to 20° C.,while a solution of 4.6 g (0.01 mol) ofbis(diphenylchlorosilyl)acetylene in tetrahydrofuran (30 mL) was slowlyadded dropwise. After the reaction, the mixture was washed 3 times witha saturated ammonium chloride aqueous solution. Then solvent was removedfrom the organic layer by distillation and the residue poured into 500mL of methanol to obtain a white polymer precipitate.

Yield 55%. Weight-average molecular weight 2200. ²⁹ Si-NMR showed askeletal structure similar to that of the polymer obtained in Example 1.

EXAMPLE 5

In a flask, 20 mL of triethylamine and 3.35 g (0.01 mol) ofbis(methylphenylchlorosilyl)acetylene were added, then the resultingmixture was stirred in an argon atmosphere with the flask cooled to 0°C., while a solution of 2.16 g (0.01 mol) of diphenylsilanediol intetrahydrofuran (20 mL) was slowly added dropwise. After the additionwas completed, the mixture was stirred at 50° C. for 2 h, then the pastymixture was dissolved in 100 mL of diethyl ether and washed severaltimes with water. The solvent was removed by distillation and theresidue poured into 500 mL of methanol to obtain a highly viscous brownoily polymer precipitate.

Yield 40%. Weight-average molecular weight 2500. ²⁹ Si-NMR, -27.6 ppm,-44.4 ppm, repeating unit: --MePhSiC.tbd.CSiPhMeOSiPh₂ O-- (Me=methylgroup; Ph=phenyl group)

EXAMPLE 6

In a flask, 30 mL of tetrahydrofuran and 2.30 g (0.01 mol) ofbis(N-ethylacetamido)dimethylsilane were added, then the resultingmixture was stirred in an argon atmosphere with the flask cooled to 10°C., while a solution of 4.22 g (0.01 mol) ofbis(hydroxydiphenylsilyl)acetylene in tetrahydrofuran (30 mL) was slowlyadded dropwise. After the reaction, the mixture was poured into 600 mLof methanol to obtain a light-brown solid polymer precipitate.

Yield 71%. Weight-average molecular weight 23,000. ²⁹ Si-NMR, -14.7 ppm,-39.6 ppm, repeating unit: --Ph₂ SiC.tbd.CSiPh₂ OSiMe₂ O-- (Me=methylgroup, Ph=phenyl group)

The invention claimed is:
 1. Poly(silethynylenedisiloxane) with a degreeof polymerization of 3 to 10,000 and with repeating units represented bythe formula:

    --R.sup.1 R.sup.2 SiC.tbd.CSiR.sup.3 R.sup.4 OSiR.sup.5 R.sup.6 O-- where R.sup.1 -R.sup.6

independently represent hydrogen atoms, alkyl groups, aryl groups, oralkenyl groups.
 2. The poly(silethynylenedisiloxane) of claim 1, whereinR1-R6 represent methyl or phenyl groups.
 3. Thepoly(silethynylenedisiloxane) of claim 2, wherein R1-R6 represent phenylgroups.
 4. A method for the manufacture ofpoly(silethynylenedisiloxane), the method comprising:reacting adisilylacetylene compound represented by the formula,

    X.sup.1 R.sup.1 R.sup.2 SiC.tbd.CSiR.sup.3 R.sup.4 X.sup.1

with a silane compound represented by the formula,

    X.sup.2.sub.2 SiR.sup.5 R.sup.6

to form poly(silethynylenedisiloxane) with a degree of polymerization of3 to 10,000 and with repeating units represented by the formula:

    --R.sup.1 R.sup.2 SiC.tbd.CSiR.sup.3 R.sup.4 OSiR.sup.5 R.sup.6 O--

where R¹ -R⁶ independently represent hydrogen atoms, alkyl groups, arylgroups, or alkenyl groups and X¹ represents a hydroxy group or alkalimetal oxide group of the formula --OM where M is an alkali-metal atom,and X² represents a chlorine atom or amide group.
 5. The method of claim4, wherein each R¹, R², R³, and R⁴ represents a phenyl group and X¹represents a hydroxy group or --OLi group.
 6. A method for themanufacture of poly(silethynylenedisiloxane), the methodcomprising:reacting a disilylacetylene compound represented by theformula,

    X.sup.1 R.sup.1 R.sup.2 SiC.tbd.CSiR.sup.3 R.sup.4 X.sup.1

with a silane compound represented by the formula,

    X.sup.2.sub.2 SiR.sup.5 R.sup.6

to form poly(silethynylenedisiloxane) with a degree of polymerization of3 to 10,000 and with repeating units represented by the formula:

    --R.sup.1 R.sup.2 SiC.tbd.CSiR.sup.3 R.sup.4 OSiR.sup.5 R.sup.6 O--

where R¹ -R⁶ independently represent hydrogen atoms, alkyl groups, arylgroups, or alkenyl groups and X¹ represents a halogen atom, amino group,amide group, alkoxy group, acyloxy group, or alkenyloxy group and X²represents a hydroxy group or an alkali metal oxide group of the formula--OM where M is an alkali-metal atom.
 7. The method of claim 6, whereinX¹ represents a chlorine atom or amide group, X² represents a hydroxygroup or --OLi group, wherein each R⁵ and R⁶ represent a phenyl group.